The present invention relates to the construction of the chassis of a sailing apparatus, and, more particularly to the construction of the steering system and the mode of attachment and of operation of the mast.
Sailing vehicles have existed since the earliest antiquity in Egypt, and then in China. In Europe, numerous types of vehicles with sails have been constructed, notably in the 16th, 17th, 18th and 19th centuries. However it was only at the beginning of the 20th century that the first competitions were organised. From the time when the use of sail vehicles, regulated for parades was codified for competitions, rigorously controlled championships have been organised. In France, there exists a National Federation of Sail Vehicles attached to the International Federation of Sand and Land Yachting. The various types of sail vehicles offered by constructors have been classed in three categories according to their sail surfaces: class 3 up to 6.50 m.sup.2 of sail, class 2 up to 10 m.sup.2 and class 1 up to 15 m.sup.2. Of course, the greater the sail surface, the greater are the forces transmitted by the mast and the stronger and hence the heavier must be the chassis. Sail vehicles of class 1 weigh between 350 and 500 kg, those of class 2 have a weight which varies from 150 to 350 kg and the lightest of class 3 weigh about 100 kg.
Certain known sail vehicles are provided with a frame of rectangular configuration and two axles each axle having two wheels, one of the axles being steerable. Other vehicles have four wheels arranged in a diamond-shaped configuration, the isolated wheels being for steering, but the majority comprise three wheels, two rear lateral wheels and one front steering wheel distinctly ahead of the mast.
Devices with four wheels arranged in the conventional manner result in poor manoeuvrability. With the majority of three wheeled sail vehicles, in which two wheels are at the rear, the pilot's seat is substantially at the level of the latter and the mast is borne forward of said rear wheels, that is to say at a point where the chassis is reduced to the "dorsal fin" which is extended up to the front wheel. This arrangement, even for a vehicle with a small sail surface, necessitates bracing of the mast, which results in considerable time for assembly and disassembly.
In known sail vehicles bracing is effected by means of three cables, two connected to the axle close to each of the rear wheels and one to the chassis, fairly close to the steering wheel. This arrangement presents a major drawback. The thrust of the wind, which is never exactly along the axis of the vehicle, acts on one wheel through the tension of the corresponding shroud while the other shroud becomes slack. The "pulled" wheel is lifted above the ground and the sail vehicle tends to tip over. To reduce the risk of the apparatus completely capsizing at this moment, the designers have been led to increase the length of the axle considerably but this does not prevent the pilot from "falling back" from an appreciable height while the wheel is recovering its contact with the ground.
In addition, the weight of the pilot acting substantially at the middle of the rear axle, that is to say at the middle of the base of the supporting triangle, it is necessary for the chassis itself to have sufficient weight to ensure stability, but that same weight is a serious handicap for the handling and transportation of sail vehicles which, by and large, can only be moved on a trailer.
Finally, the very wide track of the rear wheels with respect to the chassis required for lateral vehicular stability and control, which is essential in the general construction of the types of sail vehicles known previously, prevents any external protection of the wheels against accidental impacts, and considerably increases the risk of collision when several vehicles follow parallel paths.